Process for the bleaching of textiles



Dec. 15,1970 J, TOURD T EI'AL 3,541,513

PROCESS FOR THE BLEACHING 0F TEXTILES Filed March 12, 1969 s Sheets-Sheet 1 Dec. 15, 1970 J. TOURDOT ETAL 3,547,573

PROCESS FOR THE BLEACHING OF TEXTILES Filed March 12, 1969 3 Sheets-Sheet 2 Fig. 2

Dec 15, 1970 J. TOURDOT EI'AL PROCESS FOR THE BLEJ QCHING 0F TEXTILES 3 Sheets-Sheet 8 Filed March 12, 1969 AAA 3 u q Pn A A A f 4 1 v.\ 2\ 3 5 O O O A A .A 6 \O 17 1 q 4 m 3 2. B 8 7. 6 5 4 3 2 1 0 1 1 1 1 o o o o o o o o o United States Patent 3,547,573 PROCESS FOR THE BLEACHING 0F TEXTILES Jacques Tourdot, Paris, and Jean Breiss, Garches, France, assignors to LAir Liquide, Societe Anonyme pour IEtude et lExploitation des Procedes Georges Claude, Paris, France, and Societe dEtudes Chimiques pour lIndustrie et lAgriculture, Paris, France, both corporations of France Continuation-impart of application Ser. No. 597,879, Nov. 30, 1966. This application Mar. 12, 1969, Ser. No. 806,553 Claims priority, application France, Nov. 29, 1968,

rm. Cl. 150613/08 US. Cl. 8-108 12 Claims ABSTRACT OF THE DISCLOSURE A process for bleaching textiles containing cellulose fibers and utilizing an alkali or alkaline-earth chlorite, wherein the chlorite bath also contains an alkali or alkaline-earth bromite to which may be added a small quantity of ammonium nitrate.

The present application is a continuation-in-part of copending application Ser. No. 597,879 filed Nov. 30, 1966, now abandoned.

The present invention concerns an improvement in the process for bleaching textiles, more particularly cellulose fibers alone or blended with other fibers, by means of chlorite.

Textiles of this nature are subjected to a desizing treatment which has the object of eliminating the starchy materials which interfere with the penetration of the reactants, and after thus having been prepared they undergo the finishing operations, i.e., boiling, bleaching and dyeing.

It is known that the bleaching power of aqueous chlorite solutions is limited if they are not sufiiciently acidified or activated by various substances generally called activators. Bleaching in acid medium, for example at a pH value of 3 to 5, has proved more effective, but it has serious disadvantages; the bleaching baths become corrosive, and there is observed a considerable evolution of chlorine dioxide, which is a particularly noxious product.

It is also known from US. Pat. No. 3,083,072, filed July 8, 1957, that sodium bromite is at present industrially employed as a desizing agent for fabrics sized with starch. Sodium bromite has the property of preferentially oxidizing starch, which is thereafter eliminated by alkaline treatment. One of the methods often employed for this desizing operation in alkaline medium is carried out by impregnation of the fabric with a solution containing the bromite, the pH of which is preferably between 9 and 11, followed by storage at ambient temperature for about 10 to minutes. The fabric is thereafter ready to undergo the boiling or subsequent alkaline treatments.

It has now been found that, in addition to its desizing action, bromite has an activating action on chlorite in the bleaching of textile materials.

This new process, which constitutes an improvement in the process for bleaching textiles, more particularly cellulose fibers alone or blended with other fibers, is characterized in that the chlorite bath contains an alkali or alkaline-earth bromite.

Sodium bromite may with advantage be used in carrying out the invention. It is generally used in the form of a commercial solution containing 180 g. of active bromine per liter. By active bromine content is meant the quantity of elementary bromine having the same oxidizing power. In accordance with this notation, the quantity of active 3,547,573 Patented Dec. 15, 1970 bromine in the bromite is equal to four times its elementary bromine content.

The bromite is added to the chlorite bath in such a quantity that preferably the active bromine concentration in this bath, in the form of bromite, is between 0.8 and 3 g. per liter.

The initial pH of the bleaching bath is of the order of 9 to 11 and the final pH is of the order of 6.

It has further been found that the efficiency of bleaching and desizing can be increased by the further addition of a small quantity of ammonium nitrate to the chloritebromite bath. When used, the ammonium nitrate is added in a quantity such that the concentration in the bath of ammonium nitrate is between 0.5 and 4 g./l., preferably 2 g./ 1., when the chlorite-bromite bath contains sufiicient sodium bromite to deposit 0.8 to 3 g. of active bromine per kilogram of cloth. The initial pH of the bleaching bath is of the order of 9.510.

The process according to the invention affords numerous advantages over the conventional bleaching processes employing chlorite. In the first place, it leads to an appreciable improvement in the degree of whiteness, as also to the production of textiles which exhibit an increase in hydrophilic power, so that they may be printed or dyed without any difiiculty. Moreover, it has been found that it is possible by means of the present process in certain cases to effect a reduction of the quantity of bleaching agent as compared to the usual chlorite process, and that its reaction conditions are such that the bleaching is carried out in a pH range in which there is no evolution of chlorine dioxide. Thus, the personnel and the equipment are protected from this noxious evolution.

Thus, the activating function of bromite on a fabric which has been previously desized, for example by enzymatic means, has been very distinctly observed. When the bleaching of a fabric is carried out with, on the one hand, a bath containing chlorite alone and, on the other hand, a bath containing the same concentration of chlorite and further having added thereto 1.8 g. per liter of active bromine in the form of bromite, a distinctly higher degree of whiteness is observed in the second test, this degree of whiteness rising from 81 to 89.5 by determination with the green filter, and from 69 to 84 by determination with the blue filter. In the case of a fabric which has previously been desized and boiled, it is found that, under the same bleaching conditions as before, the degree of whiteness changes from 87 in the case of the fabric bleached by action of a bath containing chlorite alone to 90.5 in the case of the fabric treated with a bath having the same chlorite concentration but to which there has been added 1.8 g. per liter of sodium bromite. This determination was made on the green filter, and it corresponds to an improvement from 81 to 85.5 on the blue filter.

These observations clearly show the activating role of bromite under the conventional bleaching conditions.

In an extremely advantageous embodiment of the invention the desizing and the bleaching are carried out in one operation, whereby one stage of treatment is avoided, using a single bath. After an alkaline washing, there is obtained by this method an excellent desizing and an improvement in the degree of whiteness.

Thus, by treating a raw fabric on the one hand in a bath containing chlorite activated by a conventional activator, such as an acid sodium pyrophosphate or its ammonium salts, for example, and on the other hand in a bath containing the same concentration of unactivated chlorite, but to which there has been added 1.4 g. of ac tive bromine per liter in the form of bromite, a very good desizing is observed in the second treatment, the percentage of residual starch being "0.18. There is also observed a very appreciable improvement in the degree of whiteness, which changes from 82.1 in the first test to 87.9 in the second test, as determined on the green filter,

4 gether with the results. After treatment, the fabrics were only subjected to one wash in hot water.

TABLE I Degree of whiteness Initial Final Green Blue Composition of the bath pH pH filter filter Test No.2

1 Sodium chlorite, 15 g./l 9. 6 7 81 G9 2 Sodiu chlorlte. g-ll. plus 0.9 g. of active bromine 0. 9 7 s3 73 in the form of NaBrO2. 3 Sodium chlorite plus 1.8 g. of active bromine in the 10. 3 6.4 89. 5 84 form of NtB rO2 g./l. sodium chlorite). 4 Sodium chlorite, 10 g./l. plus acid sodium pyrophos- 6.4 6 84. 5 73. 5

phate to obtain a pH of 6.4. 5 Sodium chlol e, 10 g./l. plus 1.8 g. of active bromine 10. 3 5.8 86. 5 77. 5

in the form of NaBrOz.

and from 73.8 to 83.0 as determined on the blue filter.

The foregoing observations clearly indicate the double essential advantages of the use of a sodium bromite in accordance with the process of the fabric carried out simultaneously with its bleaching, and which serves as an activator for the sodium chlorite, whereby rendering unnecessary the use of a special product.

In accordance with another embodiment of the invention, the bleaching is carried out on a previously desired fabric, or an unsized fabric. The desizing may be carried out by any known method, such as sodium bromite, under the usual conditions, or optionally by enzymatic means.

By virtue of the very nature of the process, and the various ways in which it can be put into practice, it permits treatment on a common series of desized fabrics and fabrics.

The process of the invention is applicable with advantage to natural cellulose fibers, more particularly cotton, to mixtures of natural cellulose fibers and artificial fibers, such as blends of cotton and artificial fibers, and

such as blends of cotton and polyester fibers.

Comparison of the results shows the increase of the degree of whiteness in the case of tests 2 and 3 as compared with the degree obtained by the action of sodium chlorite alone in test 1. The increase is equally appreciable in the case of test 5 as compared with the degree obtained by the action of a bath containing sodium chlorite in the presence of acid sodium pyrophosphate.

(B) In this example, the same poplin is treated as in (A), but after having undergone boiling after desizing.

The operation is carried out by impregnation followed by steaming for 1 hour, 30 minutes at 95 C., under the same conditions as before.

The impregnation bath contains sodium chlorite, a wetting agent and sodium bromine employed in the form of a commercial solution containing 180 g. per liter of active bromine.

A series of bleaching tests are applied to this desized and boiled fabric, of which the various operating, bath composition and pH conditions are set out in the following Table II together with the results obtained. After treatment, the fabrics were subjected to a simple wash in boiling water and then in cold water.

TABLE II Degree of whiteness Initial Final Green Blue Composition of the bath pH pH filter filter Test No.2

1 Sodium chlorite, 15 g./l 9. 6 7 87 81 2 Sodium chlorite, 15 g.ll. plus acid sodium pyrophos- 6.4 6.4 90. 5 86 phate to obtain a pH of 6.4. 3 Sodium chlorite, l5 g./1. plus 0.9 g. of active bromine 9. 9 6. 4 00 per liter in the form of NaBrOz. 4 Sodium chlorite, 15 g./l. plus 1.8 g. of active bromine 10.3 6.7 90. 5 85. 5

per liter in the form of NaBrOz. 5 Sodium chlorite, 10 g./I. plus acid sodium pyrophos- 6. 4 6. 4 89 82. 5

phate to obtain a. pH of 6.4. 6 Sodium chlorite, l0 g./l. pqlus 1.8 g. active bromine 10.3 6. 4 90 86 per liter in the form of aBrOz.

The following examples of the application of the process illustrate the invention without in any way limiting it.

EXAMPLE I The treated fabric is a raw poplin initially containing 9.1% of starch. The weight of this poplin is g. per square meter.

(A) In this example, the raw poplin is treated after it has been initially subjected to an enzymatic desizing.

The bleaching of this poplin is carried out by the impregnation and steaming method, this second operation being performed on a roll in a housing, of the Pad Roll type, for 1 hour. 30 minutes at a temperature of 95l00 C. The bleaching bath contains 80% medium chlorite, a wetting agent and sodium bromite employed in the form of a commercial solution containing g. per liter of active bromine.

A number of bleaching tests are applied to this desized fabric. the operating Conditions, the bath composition and the nH of which are set out in the following Table l to- EXAMPLE II In this example, there is treated an initially raw fabric which has not undergone desizing and which is tightly Woven poplin. This poplin initially contains 12% starch.

This fabric is subjected to an impregnation (extent of impregnation 55%) and then to steaming with the same apparatus as before, for 2 hours at 85 C. After treatment, the fabric is washed in a soda solution diluted to 5 g. per liter in a vat, and then with hot water at 80 C., and finally with cold water, each wash hav- TABLE III 10, active bromine 1 g. per liter, wetting agent of alkylarylsulphonate type 2 ml. per liter. Without undergoing any intermediate wash, the fabric is subjected to bleaching in a sodium chlorite bath, which contains 80% chlo- Composition of the bath Degree of whiteness Test N0.:

.... 80% sodium chlorite, 20 g./liter plus 2 g./l liter of activator based upon ammonium salts plus 2gl/l. of wetting agent.

2 80% sodium chlorite, 20 g./ liter plus 1.4 g. per liter of active bromlue in the form of NaBrOz plus 2 g./liter of wetting agent.

Residual Green Blue starch, filter filter percent These results clearly show the very satisfactory desizing of test 2, carried out in a simultaneous operation with the bleaching as also the improvement in the degree of whiteness as compared with that of the fabric treated by a sodium chlorite bath containing a conventional activator based upon ammonium salts.

EXAMPLE III rite and a wetting agent. The steaming is carried out at 90 C. for 1 hour and is followed by an alkaline wash under the conditions referred to in the following.

In a second test, the raw fabric is subjected to a bromite-chlorite treatment in a simultaneous impregnating and steaming operation. The steaming lasts 1 hour at 90 C. as before on a machine of the Pad Roll" type. After bleaching, the fabric is washed on an open washing machine. Two treatments of 10 seconds are carried out in a boiling water bath containing 3 g. per liter of soda, with intermediate expressing following by rinsing in hot and cold water.

The results of these tests are set out in the following Table V.

TABLE V Degree of whitness Residual Initial Final Green Blue starch, Test No. Composition of the bath pH pH filter filter percent 1 10 g. per liter of sodium chlorite plus activator based 6. 5 81.6 74. 5 0. 1

upon phosphates for obtaining a pH of 6.5 plus 5 g./l. of wetting agent (alkylai'ylsulphonate). 2 1O g./l. of sodium chlorite plus 1.8 g. of active bromine 6 85 81.6 0. 1

per liter in the form of NaBrOg plus 5 g./l. of wetting agent (alkylarylsulphonate) The bleaching bath contains 80% sodium chlorite, a Wetting agent and sodium bromite employed in the form of a commercial solution containing 180- g. per liter of active bromine. After bleaching, the fabric is subjected to a boiling alkaline treatment 'With a soda solution in a concentration of 5 g. per liter and then to washes with hot and cold water, the fabric thereafter being expressed and dried.

The tests carried out on this raw cretonne are listed in the following Table IV.

TABLE IV This table shows the activation of the sodium bromite and the advantage of a simultaneous bleaching and desizing treatment, by means of which it is possible to obtain a degree of whiteness higher than that of a fabric subjected to bleaching by chlorite in the presence of an activator, and which gives a very well desized fabric containing a percentage of starch of less than 0.1.

EXAMPLE V A cotton cloth, an unbleached poplin, initially contain- Degree of whiteness Residual Green Blue starch, Composition of the bath filter filter percent Test N0.:

1 25 g./l. of sodium chlorite plus acid sodium pyrophosphate 79. 5 74. 8 1

to obtain a pH of 6.3. 2 25 g.ll. of sodium chlorite plus 3 g./ l. of active bromine per 80. 6 76. 1 0. 19

liter in the form of sodium bromite.

This test on a fabric very diflicult to desize shows the advantage of the process of simultaneous treatment with bromite and chlorite, by means of which it is possible to obtain a desized and bleached fabric in a single operation.

EXAMPLE IV The fabric treated in this example is a mixture of cellulose fibers and synthetic fibers. It consists of 67% of polyester fibers and 33% of cotton. This fabric initially contains 5% of starch. The extent of impregnation in all cases was In a first test, this fabric is subjected to a desizing with sodium bromite by a usual method. This desizing operation is carried out in a bath having the following ing 10.1% of starch and a degree of whiteness of 64.9 was treated.

The degree of whiteness is calculated by the formula:

composition: borax 5 g. per liter, NaOH q.s. for a pH of is a final washing of either warm water or soda.

The washing in water is preferably accomplished in a washing machine under the following condition:

1st and 2nd compartments-water at 90 C. 3rd and 4th compartments-water at 70 C. 5th compartmentcold water.

The washing with soda is also preferably effected in a washing machine under the following conditions:

Artos unrollerwater at 90 C.

1st and 2nd compartments5 g./l NaOH at 95 C. 3rd and 4th compartmentswater at 95 C.

5th compartmentwater at 70 C.

6th compartmentcold acidulated water.

(A) The bleaching of the poplin is accomplished by the process of impregnation and steaming, the second operation being effected on a roll in a housing of the Pad Roll type for 1% hrs. at a temperature of 90 C. The amount of impregnation is 70%.

In the chlorite-phosphates bleaching process, the composition of the bath is as follows: 50 ml./l. of sodium chlorite at 11.7 g./l. of crystallized monosodium phosphate; 5.7 g./l. of crystallized sodium phosphate; 3 g. of surface active wetting agent such as "Cottoclarin O.

The pH of the bath is 6.3.

The results of this test are set out in Table VI hereafter.

(B) In this test the same unbleached poplin is treated as in (A), by the bromite process of impregnation at pH 10. The operation is carried out on a foulard.

The composition of the bath is as follows: q.s. in order to deposit 1 g. of active bromine per kg. of cloth; 2 g./l. of Na CO 3 ml./l. of wetting agent, such as Montaline 1304.

In this test the amount of impregnation is 56% for about 15 minutes, that is just until the power of the oxidant disappears.

(B Test (B) is completed by washing with supplementary water carried out between the treatment with bromite and the bleaching with chlorite, the final washing being as in the other tests either with water or with soda.

The results of tests (B) and (B are set out in Table VI hereafter.

(C) In this test cotton cloth is treated, the same unbleached poplin as in (A), by the impregnation process and steaming; this second operation being effected on a roll in a housing of the Pad-Roll type for 1% hrs. at 90 C., the amount of impregnation is 70%.

Four tests are carried out with variable doses of active bromine deposited per kg. of cloth and the bath compositions are as follows:

Washing with Water Washing with soda Percent Percent Test t, ec DB starch DP B starch DP A 84. 8 1. 31 2, 400 85. J O. 47 2, 300 81. 4 1. 12 2, 260 80. l 0.20 2, 250 85. 7 0. 34 2, 210 86. 7 0. 15 2, 020 86. 2 0. 7 1, 750 85. 6 0. 35 1, 600 87. 5 1. 00 2, 180 86 0. 51 2, 000 87. 4 0. 82 2, 140 S6. 2 0.37 2, 050 87. 2 0.77 2, 100 8G. 5 0. 31 1, U250 87. 9 0. 63 2, 140 86 0.25 1, 860 87. 4 0. 64 2, 115 85. 7 0. 22 1, 870 87. 7 0.53 2,020 85. 4 0.19 1, 810 I 825. 4 0. 44 2, 050 87. 7 0. 19 1, M0 (4 23. 5 87. t5 0. 47 2, 040 87. 7 0. 18 1, 820 i 46 88. 1 0. 1, UB0 88. 4 0. 17 1, 800

EXAMPLE VI In this example different parameters of bleaching are studied on the same unbleached poplin as in the preceding example.

(I) The variations of pH of the bromite-chlorite baths, as a function of the ammonium nitrate dose, are represented by attached FIG. 1.

The pH of the baths are shown as ordinates and the quantity of NH NO in g./l. are shown as abscisses.

Four different tests are conducted. The curve 1 corresponds to a bath containing sodium bromite to deposit 2 g./l. of active bromine and 70 ml./l. of chlorite at 25%. The curve 2 corresponds to a bath containing sodium bromite to deposit 1 g. active bromine and 70 mL/l. of chlorite at 25%. The curve 3 represents the variations of pH of a bath containing sodium bromite to deposit 2 g. of active bromine and ml./l. of chlorite at 25% and the curve 4 corresponds to a bath containing sodium bromite to deposit 1 g./l. of active bromine and 50 m1./l. of chlorite at 25%.

(2) The influence of contact time 1 between the bath and the cloth before its entrance into the preheating vat of the desizer-the percent of residual starch-is shown in attached FIG. 2. The times of contact in seconds 1 are carried as abscissas, and the percents of starch are as ordinates. The curves 1, 2 and 3 correspond to desizing after washing with water. The curves 4, 5 and 6 correspond to a desizing after washing with soda. The different baths tested conatined 50 ml./l. of chlorite at 25% and variable quantities of active bromine per kg. of cloth. The curves 1 and 4 correspond to 1 g. of active bromine deposited per kg. of cloth; curves 2 and 5 correspond to 1.5 g. of active bromine deposited per kg. of cloth, and curves 3 and 6 correspond to 2 g. of active bromine deposited per kg. of cloth.

After a study of the curves, it appears that a lengthen- Duses of active bromine/kg. of cloth C1: lg. Cg: lg. C3:1.5g. (74:2g.

Chlorite solution at 25% 50 rnL/l 50 ml./l 50 ml./l 5.) rnL/l. Sodium bromite solution. Q.s. tor 1g Q.s. for 1.5 g Qs. for 2 g. Nitrateoiammoninm.. 2g./l 2g./l 2 './l.

Q.s. for pH 10. 5 g. l 5 g./l t

10 9.5 I I s 1L5 q.s. for 1 g. designates the quantity of bromite solution necessary to deposit 1 g. of active bromine/kg. of cloth. The time of contact I and the results are set down in Table VI hereafter.

The form tests and are completed by a final. washing either with water or soda.

ing of the time of contact has a beneficial effect on the amount of residual starch for a dose of 1 g. of active bromine deposited per kg. of cloth. With an increase in the dose of active bromine. one observes, not only a decrease in the amount of residual starch, but a comparison of these results as a function of time of contact and, for

a dose of 2 g. of active bromine deposited per kg. of cloth, the amount of residual starch is equivalent to a time of contact of between 15 and 45 seconds. The same conclusions are valid in the case of washing with soda and with water, as in the second case with the amount of residual starch clearly more elevated.

(3) The influence of the disage of active bromine deposed per kg. of cloth on the desizing effect is represented on FIG. 3 of the annexed drawing.

The quantities of active bromine deposited per kg. of cloth are plotted as abscissas (Br. act/kg), and the percentages of residual starch as ordinates.

The curves 1, 2 and 3 correspond to tests effected in the baths containing 50 ml./l. of chlorite at 25% and the variable quantities of active bromine per kg. of cloth, with the following times of contact: 12 seconds 1, 23.5 seconds 2, and 46 seconds 3, and followed by a washing with water.

The curves 4, 5, and 6 correspond to tests effected in baths containing 50 ml./l. of chlorite at 25% and the variable quantities of active bromine/ mg. of cloth, with the following times of contact: 12 seconds 4, 23.5 seconds 5, and 46 seconds 6, followed by washing with soda.

From a study of these curves, it appears, in the case of washing with soda, that the dose of active bromine/kg. of cloth seems to be the most important parameter. The amounts of residual starch diminish very greatly with the increase in the dose of bromite. One obtains with 2 g. of active bromine deposited per kg. of cloth amounts of residual starch less than 0.2%. Reproducible results are obtained with very difficult to desize cloths and under industrial conditions with very restrained times of contact.

In the case of washing with water, the same conclusions are reached as with the soda washing, but for 2 g. of active bromine deposited per kg, of cloth, one obtains amounts of residual starch of between 0.4 and 0.5%, whereas with a bleaching with chlorite alone, the amount is 1.3%.

It is also important to note that an increase of the dosage of bromite has a tendency to improve the resulting degree of whiteness without affecting notably the degree of polymerization of the cellulose.

EXAMPLE VII In this example a cloth is treated which is a mixture of polyester 67-cotton 33, a degree of whiteness of 64.2, determined as in Example V, and containing 10.3% of initial starch.

The cloth is bleached by the impregnation process and the steaming is effected on a roll, in a housing of the Pad Roll type for 1 /2 hrs. at a temperature of 90 C. The amount of impregnation is 65%.

The composition of the bleaching bath is as follows:

Solution of chlorite at 25 %50 ml./l. Solution of sodium bromiteq.s. to deposit 2 g. of active bromine/kg. of cloth. NH NO 2 g./l. Surface active agent-5 g./l.

After bleaching treatment the cloth is subjected to a washing in sodium carbonate at 2 g./l.

One obtains a final degree of whiteness of 88.3 and an amount of residual starch of 0.1%.

EXAMPLE VIII A polyester cloth of degree of initial whiteness of 73.3 is bleached. The cloth is bleached by the same process of impregnation, amount of 30%, and the steaming for 1 /2 hrs. at 90 C., as in the preceding example, by a bath of the following composition:

Solution of chlorite at 25 %-100 ml./l.

Solution of sodium bromiteq.s. to deposit 3 g. of active bromine/l.

Surface active-Cottoclarin O5 g./l.

As in Example VII the polyester cloth is subjected, after bleaching, to a washing with sodium carbonate at 2 g./l.

After that operation the degree of whiteness determined following the formula of Example V is 81.5.

Thus, it is seen that although the chlorite-bromite process, gives greatly improved results over prior art processes, the addition of ammonium nitrate to the bath acts to intensify the action on unbleached undersized fabric.

The addition of certain ammonium salts and in particular ammonium nitrate gives best results when the pH of the bleaching bath is adjusted by sodium bicarbonate whereby a slightly higher degree of whiteness is obtained. Variations of pH of the chlorite-bromite bleaching baths as a function of the concentration of ammonium nitrate has shown that a favorable range of pH is -10.

A study of the influence of active bromine on the desizing effect shows that a dosage of 2 g. of active bromine per kg. of chlorite for a time of contact under industrial conditions of between 15 and 45 seconds, between the bath and the cloth before the preheating, gives an increase in desizing.

What we claim is:

1. In a process for bleaching textiles containing cellulose fibers with the aid of an alkali-earth chlorite, the improvement wherein the chlorite bath consists essentially of 0.8 to 3 g. per liter of active bromine in the form of an alkali or alkaline-earth bromite.

2. A process according to claim 1, wherein the alkali bromite is sodium bromite.

3. A process according to claim 1, wherein said bleaching is carried out simultaneously with desizing of said textiles.

4. A process according to claim 1, wherein the bleaching is carried out on a previously desized fabric.

5. A process according to claim 1, wherein the bleaching is carried out on unsized fabric.

6. A process in accordance with claim 1, wherein said textile comprises a blend of said cellulose fibers with other fibers.

7. A process in accordance with claim 1, wherein the chlorite-bromite bath further contains 0.5-4 g./l. of ammonium nitrate.

8. A process according to claim 3, wherein the initial pH of the bath is between about 9 and 11.

9. A process in accordance with claim 8, wherein the final pH after bleaching of the bath is of the order of 6.

10. A process in accordance with claim 7, wherein the bath contains the necessary quantity of sodium bromite to deposit from 0.8-3 grams of active bromine/ kg. of cloth.

11. A process in accordance with claim 7, wherein the bath contains approximately 2 g./l. of ammonium nitrate.

12. A process in accordance with claim 10, wherein the initial pH of the bath is about 95-10.

References Cited UNITED STATES PATENTS 2,253,242 8/1941 MaCMahon et al. 8138 3,083,072 3/1963 Leclerc 8108X 3,120,424 2/1964 Ennenda et al. 8-108 MAYER WEINBLATT, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 p 557, 573 Dated D b J 5 1920 InvenwflQNn JEAN BRmss It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 24, "desired" should be -desized-; Column 3, line 32, insert -unsizedbefore "fabrics";

Column 1+, line 30, "bromine" should be --bromite-;

Column 6, Table 5, "whitness" should be --whiteness--;

Column 7, line 23, "sodium" should be --disodium Column 8, Table VI, line 10, "C should be --C Column 9, line 6, "disage" should be --dosage--; Column 9, line 6, "deposed" should be --deposited--;

Column 10, line 12, "undersized" should be --undesized--.

Signed and sealed this 8th day of June 1971.

(SEAL) Attest:

EDWARD M.FIETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents FORM PO-OSO (10-69) USCOMM-DC scan 

